welder in culvert

Culvert Rehab Under The Garden State Parkway

Precision Pipe and Product’s InfraSteel culvert liner was used to complete one of New Jersey’s leading infrastructure projects of 2020. Two large culvert structures were sliplined under The Garden State Parkway using the liners. The structures were rehabilitated without interruption of traffic, and now have up to a 100-year extended service life.

The Garden State Parkway (GSP) is a controlled-access toll road that stretches the north-south length of eastern New Jersey. The GSP connects the state’s southernmost tip near Cape May to the New York Stateline at Montvale. The GSP is the longest highway in the state at approximately 172 miles, and it was constructed between 1946 and 1957. The New Jersey Turnpike Authority (NJTA) maintains the parkway along with the New Jersey Turnpike.

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According to the GSP historical records, the parkway was designed to be more than just a road, it was to be a driving experience like no other. Unlike many roads built before and after, it blended functionality with the sense of freedom and adventure. At the time of its construction, the GSP was a symbol for the strength of American infrastructure and economic opportunity. It is now recognized as a historically significant resource by the New Jersey Historic Preservation Office.


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In 2019, the NJTA identified two, large failing culvert structures at Mile Posts (MP) 117.4 and 117.85, in Monmouth County that conveyed the Little Luppatatong Creek under the parkway.

McCormick & Taylor (MT) of Mount Laurel, New Jersey, was tasked with conducting an initial field inspection, alternative analysis, and final stormwater design, in order to determine whether to rehabilitate or replace the culverts.

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MT was also tasked to perform the required hydrologic and hydraulic analyses to obtain the Flood Hazard Area and Freshwater Wetland permits.

InfraSteel liners

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The culvert under the southbound lanes at MP 117.4 measured 180 ft long with an existing opening of 10 ft, 11 in. x 7 ft, 1 in. that was originally installed in an arched shape using corrugated metal plate (CMP) pipe.

According to a Sept. 21, 2018, Culvert Inspection Report, the overall condition of the culvert was assessed to be poor. This was due to numerous corrosion holes at the invert.

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The second structure, located at MP 117.85, measured 90 ft, 0 in. long with an existing opening of 14 ft, 2 in. x 8 ft, 10 in. Arched CMP with a concrete lined invert. Field inspection of the culvert revealed numerous corrosion holes throughout the entire length of the structure, along both edges of the concrete invert slab, and recorded severe roof distortion.

Armed with data of the failing structural conditions of the two existing culverts, MT assessed three viable lining options in order to determine which would provide the most economical and appropriate solution.

The three methods evaluated included:

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  • Alternative 1 – Steel Ribs & Reinforced Shotcrete Liner

  • Alternative 2 – Reinforced Shotcrete Liner

  • Alternative 3 –InfraSteel Steel Arch Pipe Liner

All three options exhibited similar hydraulic capacity improvement when compared to the existing structures.

The selection of the most appropriate solution took into consideration certain constructability issues such as; headroom clearance for workers during construction, sensitivity to storm flows, and material lead times.

Based on the above criteria, MT recommended Alternative 3 – InfraSteel Steel Arch Pipe Liner as it offered the most favorable ergonomics for the contractor’s workforce during construction, the shortest construction duration at 24 weeks, as well as the lowest overall cost at $2.610 million.

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Precision Pipe & Products, designs each InfraSteel liner to specific shapes and sizes. The liners can be manufactured in arched, elliptical or round shapes. The custom design sizes range from 26 in. to over 240 in. in diameter. InfraSteel can range from ½-in. to 2-in. thick, and with a Manning’s Coefficient of .012, the new liner would provide greater discharge capacity when compared to the existing CMP and concrete.

With InfraSteel chosen as the preferred liner solution, the project was bid and then awarded to Joseph M. Sanzari Inc., of Hackensack, New Jersey.

Sanzari began site work on the project in March 2020, but delayed in the culvert rehabilitation due to fish mating that occurs down stream in the spring and summer months. During this time period, Sanzari crews focused on building a service road across the median. This allowed for construction access, as well as future use by emergency and parkway maintenance vehicles.

Sanzari was given authorization to proceed with the culvert rehabilitations in August 2020, which began with cleaning and prepping of the existing structures. The culvert at MP 117.85 was the first structure to be lined.

The new InfraSteel sections were pushed into the host using a hydraulic excavator, and the joints were welded from the inside, utilizing OD bands that were provided attached to one end of each section of the InfraSteel liner. The OD bands helped with alignment and full penetration welding.

welder in culvert

Due to the corroded conditions inside the original structures, steel rails were placed in the invert, in order to aid in the slip-lining process.

Once the entire length was slip-lined, the annular space between the new and existing culvert was filled with grout. The grout was injected through 2-in. threaded ports installed in the InfraSteel liner.

The culvert located at MP 117.4 had to be cleaned of sediment several times due to summer rainstorms. Sanzari decided to double join the liner sections due to the length of the existing structure. This process called for two liner sections to be welded together prior to installation.

Sanzari’s installation crew also installed wheels to the bottom of the liner to assist in insertion. As with the first culvert, once the liner was positioned in place, Sanzari removed the wheels and grouted the annular space, ensuring the liner was fixed in place and structurally sound.

Both projects were completed by October 2020.

Due to the critical role the GSP serves for the commuters and visitors of New Jersey, the New Jersey Alliance for Action recorded the roadway and culvert improvements in its annual infrastructure project’s showcase.

The Team of McCormick Taylor, Joseph M. Sanzari Inc., and Precision Pipe & Products, were each recognized for their respective roles, and the project was awarded as one of New Jersey’s Leading Infrastructure Projects of 2020.

It is important for all infrastructure professionals and traveling public to be aware, and on the lookout, for the common signs of an impending culvert failure. Many potential failures can be identified from the roadway surface by paying attention to the tell-tale signs of pavement cracking, eroding embankments, and dips or drops in the road and guardrails where there are creeks or streams.

Cullom Walker is co-founder of InfraSteel Permanent Culvert Rehabilitation. Alex Sherrod is a project consultant.